Known techniques for adjusting the brightness of a display, such as a television set, a computer display, a display of a mobile phone or tablet, or the like, are based on adjusting the brightness in response to the output of one or more light sensors located close to the display. Optionally, the brightness of the display is also adjusted based on an average intensity of a video image which is rendered on the display.
The output received from such light sensors gives only a rough estimate of the light intensity in the vicinity of the display, and it does not reflect the intensity of light which actually is received by a viewer's eye. In addition, current solutions for dynamically adjusting the brightness of the display and that of external lighting in the display's environment suffer from a positive feedback loop between the external lighting and the light sensors.
U.S. Pat. No. 7,744,216 B1 discloses a solution for adjusting an intensity of a display based on measuring the dilation of a viewer's pupil. This solution suffers from the delay which is inherent to the dilation of the pupil. Moreover, it is not possible to determine that the dilation is caused by light emitted by the display.